How Will Quantum Computing Affect Bitcoin & Other Blockchain Networks?

Renowned cryptographer Adam Back does not think quantum computers (QCs) will be a threat to Bitcoin's security as crypto developers will have developed quantum resistant blockchains.

Some researchers believe QCs could be a legitimate threat to cryptocurrencies.

IBM, a New York-based IT firm with business offices in over 170 countries, recently announced that it has created a quantum computer, called Q System One, that can “operate outside the research lab for the first time.”

According to IBM’s research division, the tech firm’s newly introduced quantum computer will help greatly in the “commercialization of quantum computing.” These powerful computers may play a key role in advancements in areas such as “materials and drug discovery, financial services, and artificial intelligence”, IBM’s researchers noted.

Commenting on what effect the new IBM quantum computer might have on bitcoin (BTC) and other cryptocurrencies, Mati Greenspan, eToro’s senior market analyst, reminded his followers (via Twitter) that distributed systems expert, Andreas Antonopoulos had already answered this question.

For those of you asking about the new IBM quantum computer and the effect on BTC, @aantonop already answered this.

The only threat is if it's available to one person only. If quantum computers are available to everyone then everyone upgrades together.https://t.co/9TkmQDrbaO

During a lecture Antonopoulos delivered in February 2017, the author of soon-to-be released book “Mastering Ethereum” had said that the only threat bitcoin faces from quantum computers is if they are available to only one person or entity. However, if quantum computers can be used by everyone, then all users can upgrade their computer systems together.

In response to Greenspan’s tweet, which shared a video of Antonopoulos explaining how today’s networks will migrate to quantum resistant platforms, Adam Back, an applied cryptographer and the co-founder of Blockstream, pointed out that the present day quantum computers were still “super weak” (in terms of the number of computations they can perform in a given time period).

Although Back acknowledged that quantum computers have become “orders of magnitude” more powerful than they were in the early 1970s, he thinks that “computable functions, even those amenable to being most effectively quantum parallelized are going to be dominated by classical computers for decades.”

Back, who earned his Phd in computer science from the University of Exeter and previously served as chief security officer at data storage tech firm EMC (now Dell EMC), remarked: “[Advancements in quantum computing is] cool news, but the very least of Bitcoins tech focus for this decade.”

He added:

[There are] quite a number of Bitcoin[-related] applied crypto[graphy], protocol developments [that are focused on creating] an opt-in signature scheme upgrade with Schnorr, aggregatable + space and verification cost signatures, and that [crypto developers] know how to phase in new signature schemes. [With that said,] Bitcoin can calmly & slowly watch quantum computing [make more advancements].

It Will Take "Millions Of Years" To Crack Current Security Systems

According to a Medium post by CoinMonks, the “impact of quantum computers (QCs) on mining and the fundamental viability of the blockchain concept” will “not [be] as much of an issue.” However, the potential effect of QCs on the security of crypto wallets and addresses for “current blockchain implementations like BTC which rely on ECDSA” is a “very serious issue.”

ECDSA, which stands for Elliptic Curve Digital Signature Algorithm, “takes advantage of the assumption” that the extreme “difficulty of [the] integer factorization problem” ensures that existing cryptographically secured systems (including today’s blockchains) are sufficiently secure. This, according to CoinMonk’s post, which explains that the complex integer factorization problem involves finding the “two prime factors of a number that is 1000+ digits long.”

"Functionally Impossible" To Hack Current Cryptographically Secured Systems With QCs

Determining the prime factors of a number that’s 1000 digits (or more) long could take “millions of years” (for the most powerful computers), which is why it’s considered “functionally impossible.” And, it’s also why sensitive financial information such as credit card numbers are currently shared on the internet (without security risks) using ECDSA cryptography.

When QCs become sufficiently powerful, we will be able to use/implement Shor’s algorithm (one of the “most frequently cited algorithms when discussing QCs”) so that “the time required to factorize the product of two primes” will be reduced from “millions of years to a number of minutes/seconds and will allow the QC to derive a private key from a public key”, CoinMonk’s blog states.

Notably, “any BTC address which has broadcast a transaction has an exposed public key, [including] all of Satoshi’s one million coins [will be] exposed to this type of attack.” At present, it is not possible to accurately predict how more advanced QCs will impact digital currency platforms and other types of software applications. However, there are some crypto platforms such as Quantum Resistant Ledger (QRL) that are working on blockchain projects which will reportedly be resistant to potential attacks from QCs.